Dracaenogenins C and D, Two New 12(13→14)-Abeo-Spirostanols from the Red Resin of Dracaena cochinchinensis

The red resin of Dracaena cochinchinensis (Lour.) S.C. Chen, known as Chinese dragon’s blood, is formed through metabolic reprogramming following trunk injury, during which the original steroidal saponins are depleted and transformed. To investigate the steroidal degradation intermediates in this process, a systematic phytochemical study was conducted on the resin from Yunnan Province, leading to the isolation of 14 steroidal constituents (2 new and 12 known). The two new compounds, dracaenogenins C (1) and D (2), were identified as rare 12(13→14)-abeo-spirostanol aglycones, with 2 representing an unusual C-14α-hydroxylated derivative. Their structures, including absolute configurations, were unambiguously determined by comprehensive spectroscopic analysis (1D and 2D NMR, HRESIMS) and single-crystal X-ray diffraction. Biogenetic analysis suggests that these unusual aglycones arise from the acid-catalyzed Wagner–Meerwein rearrangement of diosgenin-type saponins via C-18 angular methyl migration (C-10→C-13) and C-ring contraction, serving as rare catabolic intermediates trapped during the metabolic shift from saponin accumulation to polyphenol biosynthesis. Furthermore, cytotoxicity evaluation against HepG2 cells revealed that while the parent glycosylated saponins (e.g., dioscin and gracillin) exhibited significant toxicity, the rearranged aglycones (1, 2, and 3) and other degradation products were devoid of cytotoxicity, supporting a detoxification mechanism during resin formation.